C Practice Exam Questions And Correct

Oklahoma Wastewater Operator Class C Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a wastewater treatment plant?
• To supply drinking water
• To remove pollutants from wastewater before discharge
• To increase the water’s alkalinity
• To desalinate water
• To remove pollutants from wastewater before discharge

Rationale: The primary goal of a wastewater treatment plant is to

remove physical, chemical, and biological pollutants to protect public health and the environment. 1 / 4

• What is the first step in the typical wastewater treatment process?
• Secondary treatment
• Tertiary treatment
• Primary treatment
• Sludge digestion
• Primary treatment

Rationale: Primary treatment involves the physical removal of large

solids and grit from wastewater before biological treatment.

• What is the main purpose of aeration in a treatment plant?
• Reduce temperature
• Add chlorine
• Provide oxygen for microbial activity
• Settle solids
• Provide oxygen for microbial activity

Rationale: Aeration supplies dissolved oxygen, which is essential for

aerobic bacteria to break down organic matter.

• Which of the following is an example of a biological treatment

process?

• Screening
• Activated sludge
• Grit removal
• Chlorination
• Activated sludge 2 / 4

Rationale: Biological treatment uses microorganisms to decompose

organic matter, and activated sludge is a common method.

• What is the function of a clarifier in wastewater treatment?
• Filter water
• Remove settled solids
• Add disinfectants
• Increase pH
• Remove settled solids

Rationale: Clarifiers allow suspended solids to settle out of

wastewater, forming sludge for removal.

• Which parameter is most commonly used to measure organic

pollution in wastewater?

• pH
• Biochemical Oxygen Demand (BOD)
• Turbidity
• Temperature
• Biochemical Oxygen Demand (BOD)

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter, indicating pollution levels.

• What is the primary purpose of disinfection in wastewater treatment?
• Reduce color
• Remove metals 3 / 4

• Kill or inactivate pathogens
• Remove solids
• Kill or inactivate pathogens

Rationale: Disinfection (commonly using chlorine or UV) reduces

disease-causing microorganisms to safe levels.

• Which of the following is a common disinfectant in wastewater

treatment?

• Sulfuric acid
• Sodium hydroxide
• Chlorine
• Hydrogen peroxide
• Chlorine

Rationale: Chlorine is widely used due to its effectiveness against

bacteria, viruses, and other pathogens.

• What is sludge?
• A type of bacteria
• Settled solids from wastewater
• Pure water
• A disinfectant
• Settled solids from wastewater

Rationale: Sludge is the solid material removed from wastewater

during primary or secondary treatment.

• / 4